Since a microwave oven which is a typical microwave heating device can directly heat food which is an object to be heated, it has become an indispensable instrument of life due to simplicity of not needing to prepare a pan or an iron pot. Up until now, a microwave oven which is popular is one in which the size of a space which accommodates food in a heating chamber where microwaves are propagated has width dimension and depth dimension of about 300 to 400 mm and height dimension of about 200 mm.
In recent years, products are being put to practical use where a heating chamber has a shape in which the bottom surface of a space which accommodates food is flat, the width dimension is set to 400 mm or more so as to be comparatively larger than a depth dimension, and the breadth is large which increases convenience as a plurality of dishes can be arranged and heated.
Additionally, along with the multi-functionalization of microwave ovens, microwave ovens are being introduced into the market with a “grill function” in addition to the existing so-called “heating function” (high-frequency wave heating which heats food by radiates microwaves onto the food). The grill function includes a means for raising the temperature of a heating plate on which food is placed, thereby heating the food via the heating pan, a means for heating food by a heating heater, or a function which cooks food by a direct fire type (the cooking finish which cooks so that the inside is juicy while the outside is crispy) by a combination of these methods.
In the related art, as shown in a configuration diagram of a conventional high-frequency wave heating device of FIG. 27, this kind of high-frequency wave heating device 300 includes a waveguide 303 which transmits the microwaves radiated from a magnetron 302 which is a typical microwave generating means, a heating chamber 301, a placing table 306 which is fixed in the heating chamber 301 for placing food (not shown) which is a typical object to be heated and which has a property that microwaves can be easily transmitted therethrough since the placing table is made of a low-loss dielectric material such as ceramic or glass, an antenna space 310 formed below the placing table 306 in the heating chamber 301, a rotating antenna 305 which is attached to the vicinity of the center of the heating chamber 301 and spans from the waveguide 303 to the antenna space 310 in order to radiate the microwaves in the waveguide 303 into the heating chamber 301, a motor 304 serving as a typical driving means which can drive the rotation of the rotating antenna 305, a heating pan 308 which is installed in the heating chamber 301 depending on the applications, a pan-receiving portion 307 which supports the heating pan 308, and a heater 309 which performs electrical heating.
In the case of heating function where an object to be heated is directly heated and warmed through high-frequency wave heating, high-frequency wave heating treatment is executed with food and the like placed on the placing table 306. The microwaves radiated from the magnetron 302 are temporarily absorbed in the rotating antenna 305 through the waveguide 303, and then, the microwaves are radiated toward the heating chamber 301 from the upper surface of a radiating portion of the rotating antenna 305. At this time, usually, in order to uniformly agitate microwaves in the heating chamber 301, the rotating antenna 305 radiates microwaves while rotating at a constant speed.
Additionally, in the case of the grill function where a direct fire type cooking is performed, food (for example, meat, fish and the like) is placed on the heating pan 308 placed on the pan-receiving portion 307. In this state, a surface portion of food is heat-treated by a heater 309 which is located above the food. On the other hand, a rear surface portion of food is heat-treated by the heating pan 308 of which the temperature has been raised by microwaves.
In heating and cooking where microwaves are concentrated on the food, the moisture inside the food evaporates excessively due to the properties of microwaves. In contrast, in the process of heating food by a heater and a heating pan, the food can be finished with a so-called direct fire type of finishing so that the surface of food is crispy while the moisture or taste is enclosed inside the food (refer to Patent Document 1).
[Patent Document 1] JP-A-2004-071216